In 1608, a Dutch optician named Hans Lippershey was the first to invent the telescope. The great Italian scientist Galileo Galilei, who became the first man to see the craters of the moon, and who went on to discover sunspots, the four large moons of Jupiter, and the rings of Saturn, introduced it to astronomy in 1609. Galileo's telescope was similar to a pair of opera glasses because it used an arrangement of glass lenses to magnify objects. This arrangement provided limited magnification, of about 30 times for Galileo, as well as a narrow field of view. Galileo was able to see only a fraction of the moon's face without the need for repositioning his telescope.
It was in 1704 that Newton announced a new concept in telescope design whereby a curved mirror, instead of glass lenses, was used to gather in light and reflect it back to a point of focus. This reflecting mirror acts like a light-collecting container: the bigger the container, the more light it can collect. Newton's novel reflector telescope design opened the door for magnifying distant objects thousands of times, far beyond what could ever be obtained with a lens.
There were many modifications to the method of focusing over the next two centuries, but Newton's fundamental principle of using a single curved mirror to gather in light remained unchanged.
In the mid-1920s, the results obtained from the Mount Wilson Observatory's 100-inch telescope demonstrated the need for a larger instrument if further advances in astronomical research were to be realized. It was the vision of astronomer George Ellery Hale to construct a 200-inch telescope. It was in 1934 that Palomar Mountain was selected as the site for the new instrument.
Thus, the Hale telescope, a telescope with a monolithic reflecting mirror, was soon to become a reality. Using Hale's approach presented a number of technical problems. A reflecting mirror, 200-inch (5 meters) in diameter would require an elaborately complex structural support system to keep it from collapsing under its own enormous weight. In addition, the larger a mirror's surface, the thicker it must be in order to withstand gravitational effects that could alter its shape. And, as the size is increased, so does the cost of the mirror, until it becomes exorbitant.
The telescope structure, whose construction began in 1928, was nearly completed by 1941 when the United States entered World War II. But the war delayed polishing of the mirror, and it was not until Nov. 20, 1947, that the finished mirror was finally installed in the telescope on Palomar Mountain.
The major change that took place was the growth in the size of the reflecting mirror, from the 6-inch mirror used by Newton to the 6-meter (236 inches in diameter) mirror of the Special Astrophysical Observatory in Russia, which opened in 1974.
The main reason astronomers build larger telescopes is to increase light-gathering power so that they can see deeper into the universe. Unfortunately, the cost of constructing larger single-mirror telescopes increases rapidly, approximately with the cube of the diameter of the aperture. Thus, in order to achieve the goal of increasing light-gathering power while keeping costs down, it has become necessary to explore new, more economical and nontraditional telescope designs. The American-built Multiple Mirror Telescope (MMT), located at the Whipple Observatory in Arizona, represents such an effort.
Since 1979, completely new and radical designs for astronomical telescopes have emerged. The Multiple Mirror Telescope (MMT), at Whipple Observatory, was the prototype, both technically and institutionally, for the next generation of large telescopes. The MMT was the world's first large-scale multiple mirror telescope, which used the combined light of six 72-inch reflecting paraboloid mirrors mounted in a single framework; where the light from all the mirrors is concentrated into a single focus. The mirrors, being under computer control, are automatically aligned at regular intervals.
The concept for using an ensemble of segmented mirrors dates back to the 19th century, but experiments with it had been few and small, and many astronomers doubted its viability. It remained for the Keck Telescope to push the technology forward and bring into reality this innovative design.
The Keck telescope is a 400-inch (10-meter) multi-mirror telescope that is comprised of 36 contiguous, adjustable mirror segments, all under computer control. It is now the largest reflector in the world and is used for both optical and infrared observations. The Keck telescope is situated on Mauna Kea on the island of Hawaii, which is the site of many major telescopes because its viewing conditions are the finest of any Earth-based observatory. This site lies at an elevation almost twice that of any other major observatory. Because it is above 40 percent of the Earth's atmosphere, there is less intervening atmosphere to obscure the light from distant stellar objects.
Even larger multimirror instruments are currently being planned by American and European astronomers.
The following prior art discloses the various aspects in the design of the large telescopes in use today.
U.S. Pat. No. 4,484,798, granted Nov. 27, 1984, to H. Howden, discloses a method of manufacturing a multiple mirror reflector for land-based telescopes. At least one series of identical segments are mounted on a rigid support to form a large primary reflector with each segment forming a part of the total profile. Each segment includes an accurately profiled reflective metal layer bonded to a concave surface of a substrate by an adhesive layer: The layer is formed on the appropriate substrate surface by transfer replication.
U.S. Pat. No. 4,776,684, granted Oct. 11, 1988, to T. Schmidt-Kaler, discloses a very large optical telescope for observing light phenomena in the wavelength region of about 0.3 to 30 or even to 300 Um. To realize a very large filled aperture it is proposed to arrange comparatively few individual reflectors around a central monolith, which can be individually adjusted optically to the central monolith which gives the reference wave front, by means of an adjustment device and/or bright starts. In this way manufacturing, polishing and transport of very large primary reflectors can be handled. Further deformations due to wind loads, temperature variations and other influences can be easily compensated. The primary reflector is carried by a yoke with the focus of the secondary mirror being in or near the elevation axis so that the usual mirror cell becomes superfluous, the beam moves only slowly with elevation and heavy instrumentation can be put directly near the focus.
Presently, the above prior art teaches of land based telescopes having large movable primary mirror structures.
What is needed is a large telescope that utilizes a stationary, segmented primary mirror. In this regard, the present invention fulfils this need.
It is therefore an object of the present invention to provide for a reflector telescope having a stationary, segmented primary mirror.
It is another object of the present invention to provide for a reflector telescope having a stationary, segmented primary mirror that is set in the equatorial position (for the Northern Hemisphere) to point at the North Star at the latitude position of its location.
It is still another object of the present invention to provide for a reflector telescope having a stationary, segmented primary mirror that is set in the equatorial position (for the Northern Hemisphere) to point at the North Star at the latitude position of its location, thereby keeping the latitude constant. The Southern Cross would serve as a reference in the southern hemisphere.
It is still yet another object of the present invention to provide for a reflector telescope having a means for traversing the primary mirror perimeter, such as a cart with eyepieces that travels on the perimeter of the stationary primary mirror at a rate of one revolution per day to follow the primary image.
These as well as other objects and advantages of the present invention will be better understood and appreciated upon reading the following detailed description of the preferred embodiment when taken in conjunction with the accompanying drawings.